"Extremely distressed by the loss of lives caused by the bus accident in Ratlam, MP. My thoughts are with the bereaved families," he tweeted.
"I wish those injured in the bus accident in Ratlam a quick recovery," Modi added in another tweet.
At least 13 people were killed and as many others injured when a private bus fell into a large water pit near Namli town in Ratlam this morning, police said.
13 people were pulled out from the bus in injured condition and referred to nearby hospitals, police said.
Unconfirmed reports said there were 40-45 passengers in the bus.
According to eyewitnesses, the bus was moving on a high speed and suddenly it overturned and fell into the large water pit.